libxml2: fix CVE-2021-3517

Fixes heap-based buffer overflow in xmlEncodeEntitiesInternal() in entities.c

CVE: CVE-2021-3517
Upstream-status: Backport [bf22713507]

(From OE-Core rev: 16ad173ba0e8f88b23c62aa8357b8afca36c2161)

Signed-off-by: Tony Tascioglu <tony.tascioglu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/libxml/libxml2/CVE-2021-3517.patch

@@ -0,0 +1,54 @@
+From df3de1376585f7a273d70023f92a530395957324 Mon Sep 17 00:00:00 2001
+From: Joel Hockey <joel.hockey@gmail.com>
+Date: Sun, 16 Aug 2020 17:19:35 -0700
+Subject: [PATCH 1/3] Validate UTF8 in xmlEncodeEntities
+
+Code is currently assuming UTF-8 without validating. Truncated UTF-8
+input can cause out-of-bounds array access.
+
+Adds further checks to partial fix in 50f06b3e.
+
+Fixes #178
+
+CVE: CVE-2021-3517
+Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/bf22713507fe1fc3a2c4b525cf0a88c2dc87a3a2]
+
+Signed-off-by: Tony Tascioglu <tony.tascioglu@windriver.com>
+---
+ entities.c | 16 +++++++++++++++-
+ 1 file changed, 15 insertions(+), 1 deletion(-)
+
+diff --git a/entities.c b/entities.c
+index d575e9d1..7cdbc4de 100644
+--- a/entities.c
++++ b/entities.c
+@@ -666,11 +666,25 @@ xmlEncodeEntitiesInternal(xmlDocPtr doc, const xmlChar *input, int attr) {
+ 	    } else {
+ 		/*
+ 		 * We assume we have UTF-8 input.
++		 * It must match either:
++		 *   110xxxxx 10xxxxxx
++		 *   1110xxxx 10xxxxxx 10xxxxxx
++		 *   11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
++		 * That is:
++		 *   cur[0] is 11xxxxxx
++		 *   cur[1] is 10xxxxxx
++		 *   cur[2] is 10xxxxxx if cur[0] is 111xxxxx
++		 *   cur[3] is 10xxxxxx if cur[0] is 1111xxxx
++		 *   cur[0] is not 11111xxx
+ 		 */
+ 		char buf[11], *ptr;
+ 		int val = 0, l = 1;
+ 
+-		if (*cur < 0xC0) {
++		if (((cur[0] & 0xC0) != 0xC0) ||
++		    ((cur[1] & 0xC0) != 0x80) ||
++		    (((cur[0] & 0xE0) == 0xE0) && ((cur[2] & 0xC0) != 0x80)) ||
++		    (((cur[0] & 0xF0) == 0xF0) && ((cur[3] & 0xC0) != 0x80)) ||
++		    (((cur[0] & 0xF8) == 0xF8))) {
+ 		    xmlEntitiesErr(XML_CHECK_NOT_UTF8,
+ 			    "xmlEncodeEntities: input not UTF-8");
+ 		    if (doc != NULL)
+-- 
+2.25.1
+

meta/recipes-core/libxml/libxml2_2.9.10.bb

@@ -24,6 +24,7 @@ SRC_URI = "http://www.xmlsoft.org/sources/libxml2-${PV}.tar.gz;name=libtar \
            file://CVE-2019-20388.patch \
            file://CVE-2020-24977.patch \
            file://fix-python39.patch \
+           file://CVE-2021-3517.patch \
            "
 
 SRC_URI[libtar.md5sum] = "10942a1dc23137a8aa07f0639cbfece5"